Low melting paraffin wax



Patented Feb. 23, 1954 2,670,323 LOW MELTING PARAFFIN WAX Melvin V.Hunter, Richmond, and John R. Segesser, El Cerrito, Calif., assignors toCalifornia Research Corporation, San Francisco, Calif., a corporation ofDelaware No Drawing. Application January 6, 1951, Serial No. 204,816

6 Claims. 1

The present invention relates to improved petroleum paraffin waxproducts and more particularly to superior low-melting refined paraflinwax products.

Waxes derived from petroleum are classified broadly as parafiin wax andmicrocrystalline or amorphous wax. Parafiln waxes which are obtainedfrom distillates have relatively low melting points and low tensilestrengths, whereas mlcrocrystalline waxes have relatively high meltingpoints and high tensile strengths. The present invention is notconcerned with the microcrystalline waxes but rather relates to theparafiin Waxes. Of these there are two general types, the normal orstraight-chain paraflin waxes and the non-straight-chain parafiin waxes.For the same boiling point or molecular weight range, thenon-straight-chain paraflin waxes have lower melting points than thenormal paraflln waxes. For example, as compared to an oilfreestraight-chain paraffin wax having an average melting point of 140 F. A.M. P., a nonstraight-chain parafiin wax of approximately the samemolecular weight has an average melting point of about 119 F. A. M. P.In general, the non-straight-chain paraffin waxes having molecularweights about the same as the normal paraffin waxes having averagemelting point up to about 165 F. A. M. P. will have melting points belowabout 125 F. A. M. P. (The term A. M. P." refers to American MeltingPoint, as defined in ASTM D87-42). Further, the non-straightchainparafiin waxes are more readily soluble in selective solvents such asare normally used for solvent deoiling slack waxes obtained fromdewaxing waxy lubricating oil stock.

The present invention is directed to improved parafiin wax productcontaining particular ratios of certain of the above-mentionedstraight-chain and non-straight-chain paraffin waxes. An object of thisinvention is to provide a low-melting parafiin wax composition ofsuperior properties. It is a more particular object of the presentinvention to provide an improved low-melting petroleum paraflin wax forcoating paper products such as milk cartons.

Briefly, we have found that a low-melting refined petroleum parafiin waxof superior properties results from the combination of at least 20,

but less than 35 volumes of non-straight-chain paraffin waxes havingmolecular weights predominately in the range of 350-525, preferably400-500, and 80 to 65 volumes of straight-chain parafiin waxes having anaverage melting point of about 127-1 M. P." The resulting product has anaverage melting point within the range of -135 F. A. M. P., the averagemelting point of the straight-chain wax portion alone being sufficientlyhigh to yield in combination with the non-straight-chain wax, a waxproduct with the desired average melting point. Since each of thecomponents individually have low tensile strengths, the high tensilestrength of the above wax composition is an unexpectedly advantageousresult.

Our new wax product, in addition to having an increased tensilestrength, is less brittle and has improved adhesiveness towards paperproducts. The improved low-melting paraffin wax product is excellent forcoating paper cartons such as those used for milk. With these waxproducts, strong and waterproof films on milk cartons are obtained witha minimum amount of wax, and the resultant coating has less tendency tocrack off than wax coatings heretofore obtained. Thin films of these newwaxes are flexible and have high resistance to fracture on suddenchilling. In storage of milk cartons coated with the present waxes, lessbulging occurs and fewer leakers are found.

As stated above, the present wax compositions have average meltingpoints in the range of 125135 F. A. M. P., thus including within thescope of the various wax grades of 125/ 127, 128/130, 133/135 and thebroader grade 125/130.

The wax product of the present invention can be obtained in severalWays. For example, each of the desiredstraight-chain parafiin waxes andthe desired non-straight-chain paraflin waxes can be obtained separatelyor isolated (i. e., completely freed from oil by solvent deoiling) andthereafter combined in the proper ratio. Likewise, concentrates of thedesired non-straight-chain paraffin wax in admixture with minor amountsof tolerable normal paraffin wax can be produced and combined in theproper ratio with normal parafiin wax concentrates containing smallamounts of non-straight-chain waxes. Prefer ably, selected slack waxesderived from primary and secondary waxy oils are combined prior tosolvent-deoiling, whereby, upon deoiling, the superior wax compositionof the present invention is produced. This process, as more particularlyset forth in the copending application of Charles J. Halamka and Lynn R.LaPorte, Serial No. 204,806, filed January 6, 1951, includes thefollowing steps of solvent-dewaxing a waxy oil to produce a dewaxed oilof low pour point and a primary slack wax. The primary slack wax is thenfractionated into-primary wax distillates of relatively narrow boilingpoint ranges including a low-boiling fraction which, bysolvent-deoiling, yields waxes having an average melting point in therange of 127-140" F. and a higher-boiling, intermediate fraction which,by solvent-deoiling, yields waxes having. an average melting point of135-16091. A. M..P., preferably at least F. higher than the waxresulting from normal solvent-deoiling of the low-boiling primary slackwax distillate selected. Ordinarily, the selected low-boiling andintermediate higher-boiling :primary slack wax distillates are adjacentfractions. although in many cases the boiling-range. ofj thehigher-boiling fraction will overlap that of the lower-boiling fractionand in some cases advantageously overlaps the whole or up to 50% of thelower boiling fraction. The higher-boil ng.

primary slack wax distillate thereafter is solventflPniled to produce awax product and a foots, oil. The foots oil, which is a secondary waxy,oil, is .then solvent-dewaxed. to. obtain a high quality lubricatingoil component and. a secondary slack wax. At least a portion of thesecondary slack wax-is then combined with the selected. low-boilingprimary slack wax distillate, and the admixture is solvent-deoiled toproduce the desired wax product.

For the purposes of this invention, a. waxy oil is an oil, preferably alubricating oil stock, derived from crude petroleum containingparafflnic compounds which are normally solid atroom temperature. Thepercentage of such petroleum paraifin wax may vary from 1 to 25% in avirgin crude oil, or from 2 to 50% in topped crude oil or distillatefractions or in waxy raffinates obtained from solvent treating ordeasphalting distillate fractions or residua. Theslack waxes obtained bydewaxi-ng usually contain about -60% of azero F. pour point oil,although the oil content can be as low as 2-3%. The'wax in thelowboiling distillates of primary slack wax is substantially all (i. e.,more than about 90%) normal or straight-chain paraffinic compounds. Inthe: secondary slack. waxes as obtained by-solventdewaxing a foots oilresulting from deoiling a primary slack wax distillate, the wax ispredominately ('i. e., more than about 75%) non-straightchain paralfiniccompounds. Especially suitable for the present invention are primaryslack waxes derived from petroleum residua, including residua such asviscous lubricating oil stocks which are pretreated such as bydeasphalting or refining with aromatic-removing solvents or the like.

As indicated hereinabove, the desired nonstraight-chain paraflin waxesare concentrated in the slack wax distillate fractions boiling abovethose primary slack wax distillate fractions'which, on deoiling, yield awax product with an average melting point of above about 130 F. A. M. P.Hence. foots oils obtained in solvent deoiling to produce such highermelting waxes are suitable sources for the non-straight-chain paraiiinwaxes. Preferably employed are the foots oils obtained in solventdeoiling primary slack wax distillates to produce waxes having anaverage melting point above about 140 F. A. M; P. and up to about 165 F.A. M.-P. As described hereinabove, such foots oil is subjected tosolvent dewaxing to produce a low pour'point oil and a secondary slackwax which either can be separately deoiled or combined with the selectedlow-boiling slack wax distillate before. d oi a Also from. de ailinbroader boiling range primarywaxdistillates to yieldwaxes of.low-average melting point. ipots of about p. s. i-

4 amounts of the desired ncn-straight-chain para!- fin waxes; such footsoils can be dewaxed to produce a secondary slack wax which then can befractionated to separate the upper boiling 30-60% containing the desirednon-straight-chain parafwaxes.

In preparing .the improved refined petroleum paraflin wax composition ofthe present invention, the dewaxing and deoiling operations are carriedout by the various well-lmown methods involving chilling in the presenceof solvents or diluents, including, for example, ketones such as methylethyl ketone, aromatic hydrocarbons such as benzene, alcohols such asiscpropyl alcohol,

In solvent ,dewaxing, ordinarily conducted with a filtering temperatureof about 0 F. to -15 F., the primary object is to obtain a substantiallydewaxed lubricating oil, 1. e., an oil with a zero F. or lower pouroint; also obtained is the primary slack wax. In deoiling, usuallyconducted with a liltering temperature of about 35-55 F., the;primaryslack wax is segregated into oil-free wax and foots oil. The primaryslack wax is fractionated, at stated above, into relatively narrowboiling distillates, preferably in a vacuum frac tionator. While thefractions are segregated ordinarily on the basisof the average meltingpoint of the waxes produced by deoiling the distillates, it can begenerally stated for purposes of illustration that a typical primaryslack wax derived from a California waxy crude residuum (25-30% from.crude) can be suitably fractionated into three cuts: No. 1 out, No. 2cut, and No. 3 cut with average boiling points (at atmospheric pressure)of about 800 F5900 F. and 1050 F., respectively. For comparativepurposes, the deciling of out No. 1 alone yields a wax having an A. M.P. of about 135-140" R, the lower-boiling 50-60% of out No. 1 yielding awax melting at -130 F. A. M. P. Deoiling of No. 1 and No. 2 cutstogether yields a wax with a 143-150 F. A. M.P.

To illustrate the present invention, a deoiled low-meltingstraight-chain paraffin wax obtained by solvent deoiling thelower-boiling 50-60% of the above-described No. 1 cut was taken forcomparison. This wax had an average melting point of about 129 F. A. M.P. and a tensile strength To this was added 30% of a predominatelynon-straight-chain paraflin wax (i. e., about 80% non-straight-chainwax) obtained by deoiling the secondary slack wax from dewaxing thefoots oil produced during deoiling the above-described No. 1 and No. 2cuts. The resultant blend had an average melting point of about 127 F.A. M. P. and a tensile strength of 263 p. s. i. In another instance, 30volumes of the above secondary slack wax was added to '70 volumes of theheretofore-described whole No. 1 cut of the primary wax distillate, andthe admixture solvent deoiled. The product had an average melting pointof about 129 F. and a tensile strength of 298 p. s. i. In anotherinstance, a product was produced by deoiling a blend of 27 volumes ofthe above secondary slack wax, 63 volumes of the hereinabove-describedwhole No. 1 cut, and 10 volumes of a third slack wax (-containing a50-50 mixture of non-straight-chain and normal parafdn waxes) obtainedby dewaxing thefoots oil resulting from, deoiling another, portion ofsaid whole-NO. 1 cut. The product. had anavera e mel nepoi o h ut1293-5.A'..,M. P.

e1 e;. ei s vlimeremain.resealable snag .t'msi siteee -a ut 51?- atVarious ways of producing the improved lowmelting wax compositions ofthe present invention can be employed other than the specific preferredembodiments given above for purposes of illustration. While the presentwax compositions consist essentially of petroleum parafiin waxes of thedesignated types and in the specified ratios, small amounts of additivesfor various purposes can be incorporated into the final composition.Thus, the term "consisting essentially of as used in the claims meansthat the composition is made up almost entirely of the ingredientsrecited and these ingredients are the main and characterizing ones, butthis expression does not exclude the presence of minor amounts of otheringredients which are commonly in wax compositions or which do notchange the essential character of the composition. Thus, small amounts(from 0.01 or less up to 1 or 2%) of antioxidants such as variousphenolic antioxidants, e. g., 2,6-di-tertiary-butyl 4-methyl phenol,tensile strength improvers such as microcrystalline wax, and the likecan be incorporated in the final wax composition.

We claim:

1. A substantially oil-free paraffin wax composition having an averagemelting point within the range of 125-135 F. A. M. P. which consistsessentially of at least 20% but less than 35% of non-straight-chaindistillate parafiin waxes having molecular weights predominately in therange of 350-525 and the remainder being straightchain distillateparaflin wax having an average melting point within the range of 127-140F. A. M. P. and an average molecular weight substantially below that ofsaid non-straight-chain wax.

2. A substantially oil-free parafiin wax composition having an averagemelting point within the range of 125-135 F. A. M. P. which consistsessentially of at least 65% of a straight-chain distillate parafiin waxhaving an average melting point of 127-140 F. A. M. P. and at least 20%of a non-straight-chain distillate parafiin wax having an averagemelting point below about 125 F. A. M. P. and an average molecularweight of about 400-500 said straight-chain wax having an averagemolecular weight substantially below that of said non-straight-chainwax.

3. A substantially oil-free paraifin wax composition having an averagemelting point within the range of 125-135 F. A. M. P. and having a hightensile strength which consists of at least 20% but less than 35% of aparafiin wax selected from non-straight-chain.distillate paraflin waxeshaving molecular weights predominately in the range of 350-525, and theremainder consisting essentially of straight-chain distillate paraffinwax having an average melting point Within the range of l27-140 F. A. M.P. and an average molecular weight substantially below that of saidnon-straight-chain wax, the average melting point of said straight-chainwax being sufiiciently high to yield an improved tensile strength waxproduct with the desired average melting point within the range of125-135 F. A. M. P.

4. A substantially oil-free parafiin wax composition having an averagemelting point within the range of 125-135 F. A. M. P. and having a hightensile strength which consists essentially of -80% of a straight-chaindistillate paraffin wax having an average melting point of about 127-140F. A. M. P. and at least 20% but less than 35% of a non-straight-chaindistillate paraflin wax having an average molecular weight in the rangeof 400-500 said straight-chain wax having an average molecular weightsubstantially below that of said non-straight-chain wax.

5. The paraffin wax composition of claim 4, wherein thenon-straight-chain paraflin wax is obtained from a secondary slack waxproduced upon solvent dewaxing a foots oil resulting from solventdeoiling a primary slack wax distillate which by deoiling yields a waxproduct having an average melting point above about 140 F. A. M. P.

6. A substantially oil-free distillate paraffin wax composition of hightensile strength and having an average melting point within the range of-135 F. A. M. P. which consists essentially of 20 to 35% ofnon-straight-chain distillate paraffin wax having molecular weightspredominantly in the range of 400-450 and the remainder beingstraight-chain distillate parafiin wax having an average melting pointwithin the range of 127-140 F. A. M. P. and an average molecular weightsubstantially below that of said non-straight-chain wax, saidstraight-chain wax alone having a tensile strength substantially lowerthan the final composition.

MELVIN V. HUNTER. JOHN R. SEGESSER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,937,518 Henderson et al. Dec. 5, 1933 2,102,516 Coster Dec.14, 1937 2,127,668 Adams et al. Aug. 23, 1938 2,361,582 Adams et al Oct.31, 1944 2,467,959 Bowman et al Apr. 19, 1949 2,603,589 Schaerer July15, 1952 2,611,734 Ridenour Sept. 23, 1952

1. A STUBSTANTIALLY OIL-FREE PARAFFIN WAX COMPOSITION HAVING AN AVERAGEMELTING POINT WITHIN THE RANGE OF 125-135* F. A.M.P. WHICH CONSISTSESSENTIALLY OF AT LEAST 20% BUT LESS THAN 35% OF NON-STRAIGHT-CHAINDISTILLATE PARAFFIN WAXES HAVING MOLECULAR WEIGHTS PREDOMINANTLY IN THERANGE OF 350-525 AND THE REMAINDER BEING STRAIGHTCHAIN DISTILLATEPARAFFIN WAX HAVING AN AVERAGE MELTING POINT WITHIN THE RANGE OF127-140* F. A.M.P. AND AN AVERAGE MOLECULAR WEIGHT SUBSTANTIALLY BELOWTHAT OF SAID NON-STRAIGHT-CHAIN WAX.